The present invention relates to a lens presser for holding an eyeglass lens, which is used when the eyeglass lens is processed, and an eyeglass lens processing apparatus having the same.
In an eyeglass lens processing apparatus, an eyeglass lens is rotated while being held (chucked) by two lens chucking shafts, and a periphery of the lens is processed by a processing tool such as a grindstone so as to substantially coincide with a desired target lens shape. As a method of holding (chucking) a lens, there are two kinds of methods, optical-center chucking in which the lens is be held so as to conform (align) an optical center of the lens to a holding (rotation) axis of the lens, and boxing center chucking in which the lens is held so as to conform (align) a geometric center (boxing center) of the target lens shape, which is laid out in the lens, to the holding axis of the lens.
In the boxing center chucking, since a lens is held in a position deviated from the optical center, such a lens presser is proposed that can correspond to a curved surface of the rear refractive surface of a lens (refer to JP-A No. 2002-310146). The above lens presser is provided with a movable member to which an abutting member is attached. The movable member is tiltable (rotatable), centered on a position of a base member attached to a lens chucking shaft.
As shown in FIG. 10, another lens presser is proposed in which a bowl-shaped movable member 903 having an abutting portion 901 is attached to a curved surface of a base member 905 attached to a lens chucking shaft 900R through a screw 907.
In the former lens presser, however, the movable member does not move smoothly and a lens cannot be stably held, because the tilt (rotation) center of the movable member is present in the base member side. On the other hand, in the latter lens presser, the movable member is easily rotated with respect to the lens chucking shaft centered on the holding axis of a lens, and thus the lens cannot be stably held.
In processing a lens, processing water is used for cooling the processed portion of the lens and washing off ground waste of the lens. However, if minute chaff enters between the base member and the movable member of the lens presser, the movable member does not move smoothly. In this case, the base member and the movable member are separated so as to be cleaned, but it is not easy to separate them in the related lens presser.